package com.hmdp.utils;


import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.LOCK_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.LOCK_SHOP_TTL;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        // 逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }


    public <R, ID> R queryWithPassThrough(String strKey, ID id, Class<R> type, Function<ID, R> function, Long time, TimeUnit unit) {

        String key = strKey + id;
        // 1. 从redis中查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);

        // 2. 判断是否存在
        if (StrUtil.isNotBlank(json)) {
            // 3. 存在，直接返回
            return JSONUtil.toBean(json, type);
        }

        // 4. 不存在，查询数据库
        R r = function.apply(id);

        if (r == null) {
            this.set(key, "", time, unit);
            return null;
        }
        this.set(key, r, time, unit);
        return r;
    }


    public <R, ID> R queryWithLogicalExpire(String strKey,ID id,Class<R> type, Function<ID, R> function, Long time, TimeUnit unit) {

        String key = strKey + id;
        // 1. 从redis中查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);

        // 2. 判断是否存在
        if (StrUtil.isBlank(json)) {
            // 3. 不存在，直接返回
            return null;
        }

        // 4.命中 先把jison转成对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        R r = JSONUtil.toBean(data, type);

        LocalDateTime expireTime = redisData.getExpireTime();

        // 5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            // 5.1未过期，直接返回店铺信息
            return r;
        }
        // 5.2过期 需要建立缓存信息
        // 6.建立缓存
        // 6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);

        // 6.2 判断是否获取锁成功
        if (isLock) {
            // 6.3 成功 开启独立线程 实现缓存
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    R r1 = function.apply(id);
                    this.setWithLogicalExpire(key, r1, time, unit);
                } catch (Exception e) {
                    throw new RuntimeException();
                } finally {
                    unlock(lockKey);
                }
            });
        }

        // 6.4 失败 返回过期的商品信息
        return r;
    }


    // 获取锁
    public boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.MINUTES);
        return BooleanUtil.isTrue(flag);
    }


    // 解锁
    public void unlock(String key) {
        stringRedisTemplate.delete(key);
    }
}
